B737 Flight Deck and Operating Documentation

The Boeing 737's successive series include the original 737, the 737 Classic, the Next Generation (NG) and the 737 MAX, all on one type certificate and all flown on a single type rating. A pilot moving between them learns the differences, not a new aeroplane.

A 737 crew works from a set of documents: the flight crew operations manual (FCOM), with its limitations, normal procedures and system descriptions; the quick reference handbook (QRH) of non-normal checklists; the dispatch deviation guide (DDG) or the operator's equivalent, to which the FCOM refers when a fault is found on the ground; and the performance data the crew enter into the flight management computer. Systems detail in this article follows the 737 NG FCOM; where the MAX differs, it says so. For the general framework see operations manual and flight crew documentation.

737 generations: Classic, NG and MAX

The FAA Flight Standardization Board (FSB) gives every 737 model, from the -100 to the MAX, the single type rating B-737, because they are related aircraft on one type certificate. In the EASA type certificate data sheet the MAX flight crew data carry the same Boeing document number as the NG's, though the wording of the licence endorsement is for each authority to confirm. Between older series, such as the original 737 and the Classic, the FSB requires supervised line flying of two legs and at least 5 hours; between the NG and the MAX it requires none, in either direction.

The 737-8 is 39.5 m long like the 737-800, its nose gear 8 in longer to give the bigger engines ground clearance. The MAX family also includes the 737-7, the 737-8200 and the 737-9, whose 42.11 m matches the 737-900ER's length; the 737-9 and 737-8200 can have a mid exit door on each side. MCAS, part of the MAX's speed trim system, adds nose-down stabiliser trim at high angle of attack, in manual flight with the flaps up, because the larger, more forward engines would otherwise lighten the column near the stall more than the rules allow. The NG has speed trim but no MCAS.

From the NG to the MAX the FSB's master differences requirement is Level B training and checking, aided instruction such as computer-based training, plus the Appendix 7 special training, which no pilot may skip before operating the MAX. It includes simulator events on MCAS, the cross-FCC trim monitor and an erroneous high angle of attack on take-off, which need a MAX simulator, and manual stabiliser trim exercises that may be flown in an NG simulator. See class and type ratings.

The flight deck and its normal procedures

Boeing writes its normal procedures for a trained crew and assumes that all systems work normally and that the automatics (LNAV, VNAV, autopilot, autothrottle and autoland) are fully used, without ruling out manual flying for proficiency. For each phase of flight the procedures verify that the aeroplane's condition is satisfactory and the flight deck configured correctly. They are done from memory, following a scan flow of the panels that may be adapted as needed, and they assume coordination with the ground crew before hydraulic pressurisation, flight control movement or aeroplane movement.

Preflight and postflight duties are divided between captain and first officer; phase-of-flight duties between the pilot flying (PF), who taxies, controls the flight path and airspeed, configures the aeroplane and navigates, and the pilot monitoring (PM), who reads checklists, communicates, does tasks the PF asks for and monitors. The mode control panel is the PF's responsibility; CDU entries in flight are normally made by the PM and executed only after the other pilot has verified them. The captain is the final authority for all tasks directed and done.

The lights follow fixed colours: red for warnings, amber for conditions that need timely attention, blue for information such as power availability and valve positions, and green for a fully extended configuration such as gear and leading edge devices. Two system annunciator panels on the glareshield repeat the systems of the forward overhead, aft overhead and fire control panels and trigger the MASTER CAUTION lights. Pushing MASTER CAUTION puts the lights out and resets the system. Pushing an annunciator panel recalls any existing conditions, including simple faults, single faults in redundant systems that are stored without lighting MASTER CAUTION. Before engine start the crew use the system lights to check each system's configuration; after start the master caution system brings faults to their attention.

The FCOM's Limitations chapter combines AFM limitations, AFM operational information and non-AFM operational information, leaving out what is already in procedures or on placards and displays. A # marks a memory item. For weight limitations, the FCOM states that the AFM governs if the two disagree.

Preliminary preflight procedure

The preliminary preflight procedure assumes that the Electrical Power Up supplementary procedure is complete (see B737 electrical system). Its main items are:

• IRS: a full alignment is recommended before each flight, otherwise the Fast Realignment supplementary procedure. The mode selectors go OFF, then NAV; the ON DC lights come on and go out, and the ALIGN lights come on.
• Crew oxygen: a pressure drop test, needed at one station only. The pressure must not fall by more than 100 psig; a rapid or larger drop, or a slow recovery, suggests the cylinder valve is not fully open.
• Emergency equipment: fire extinguisher checked and stowed, crash axe and escape ropes stowed.
• Panels: FLIGHT DECK ACCESS SYSTEM switch guard closed; ELT, PSEU and GPS lights out; SERVICE INTERPHONE OFF; ENGINE panel with REVERSER and ENGINE CONTROL lights out and EEC switches ON; PASSENGER OXYGEN switch guard closed, since operating it drops the passenger masks, with the PASS OXY ON light out; FLIGHT RECORDER switch guard closed with its OFF light lit.
• Tests: the MACH AIRSPEED WARNING TEST switches, one at a time, each sounding the clacker; and the stall warning test, which needs the AC transfer buses powered for up to 4 minutes. With hydraulic power off the leading edge flaps can droop enough to give an asymmetry signal and fail the test; the crew then obtain clearance, pressurise system B with its electric pump, retract the flaps and repeat the test.

The CDU preflight procedure may start any time after the preliminary preflight. Initial data and navigation data must be entered before the flight instrument check of the preflight procedure, and performance data before the Before Start checklist.

Non-normal checklists

The QRH holds the non-normal checklists (NNC). If a red warning or amber caution light comes on during or after engine start, the crew do the respective NNC; on the ground they also check the DDG. If an amber caution appears on recall and goes out after a master caution reset, the NNC is not needed, only the DDG.

Some checklists start with recall items, done from memory, followed by reference items read from the QRH. In Airspeed Unreliable, checking the probe heat ON and cross-checking the captain's, first officer's and standby airspeeds are reference items after the recall steps. When the cabin altitude warning horn sounds in flight above 10,000 ft MSL, the crew immediately don oxygen masks with the regulators at 100 %, establish crew communication and do the CABIN ALTITUDE WARNING or Rapid Depressurization checklist. The emergency descent follows if the aeroplane is above 14,000 ft MSL and the cabin cannot be controlled, or if cabin pressure is lost. Checklists can also override limitations: the CARGO FIRE and SMOKE/FUMES REMOVAL checklists allow packs in HIGH despite the restriction for take-off, approach and landing.

After the MAX accidents several checklists were revised, and the current Runaway Stabilizer recall items are shared by the NG and MAX QRHs. The checklist now covers stabiliser movement that is continuous or wrong for the conditions, makes pitch control with the column and speed control with the thrust levers memory steps, and asks for main electric trim before both STAB TRIM CUTOUT switches; a note adds that reducing airspeed makes manual trimming easier. On the MAX, AOA DISAGREE leads to the Airspeed Unreliable checklist.

Dispatch deviation guide

The FCOM refers the crew to the Dispatch Deviation Guide (DDG), or the operator's equivalent, in three situations: on the ground, when a red warning or amber caution light comes on during or after engine start, after the respective NNC; when an amber caution seen during recall goes out after a master caution reset; and when a system annunciator light fails the recall test, in which all twelve system annunciator lights must come on while the press-to-test is held.

What may be deferred is set by the operator's minimum equipment list. Dispatch with the fuel tank nitrogen generation system inoperative, for example, is acceptable under MEL procedures, because the tanks are protected primarily by excluding ignition sources. For the 737 MAX, the revised FAA master MEL requires both flight control computers for passenger dispatch and no longer allows the speed trim function, the SPEED TRIM FAIL light or the control wheel trim switches to be deferred.

Performance data and the CDU

Take-off performance is usually calculated before flight with an electronic flight bag performance application or the operator's other performance tools. Whatever the tool, its results reach the aeroplane through the CDU, and the FCOM's rules for entering them guard against the commonest errors:

• on the PERF INIT page, the zero fuel weight must never be entered in the gross weight boxes, or the FMC computes performance data with significant errors; fuel on the CDU, the dispatch papers and the fuel gauges must agree, as must the gross weight and cruise CG;
• on the TAKEOFF REF page, page 2/2 is completed before page 1/2;
• the thrust reduction altitude accepts entries from 800 to 9,999 ft;
• the amber NO VSPD flag stays on the PFD on the ground until V1 and VR are entered or set;
• assumed temperature reduced thrust may reduce thrust by up to 25 % below any certified rating; it is not used on runways with standing water, slush, snow or ice, with possible windshear, or with antiskid inoperative. An R-TO display does not show whether the reduction comes from an assumed temperature, a derate or both;
• TAT on the engine display must not be used in place of outside air temperature for take-off performance.

In flight the FMC's own performance database, holding the aeroplane's drag and engine characteristics, maximum and optimum altitudes and speed limits, removes the need to refer to a performance manual.

Library articles are written for study and exam preparation. They do not replace your aircraft's approved documentation, your operator's procedures or the regulations themselves.